<style>
    body {
        background: green;
    }
</style>
<script src="include.js"></script>
<script>
    asyncTest(done => {
        let link = document.createElement("link");
        link.setAttribute("rel", "stylesheet");
        link.setAttribute("href", "body-background-color-red.css");
        link.setAttribute("media", "print");
        document.head.appendChild(link);

        window.onload = function () {
            println("document background: " + getComputedStyle(document.body).backgroundColor);
            done();
        };
    });
</script>